Despite ramped-up competition, Apple should achieve at least 22.5 million iPad sales in 2011 — and that’s not analyst bluster or wishful thinking but the conservative estimate of Apple competitor, ViewSonic.

ViewSonic expects Apple to grab 50 percent of a projected 45 million tablet sales next year. The competitor says it is aiming to grab 10 percent of the remaining non-iPad market, approximately 2 million devices.

The company’s Asia Pacific president, Alan Chang, told Digitimes that tablets are replacing netbooks at the firm. “Chang also pointed out that the company hopes its tablet PC shipments could reach over 5,000 units per month and it will gradually phase out of the netbook market in Taiwan,” the report explains.

The future iPad competitor will be a 10-inch model using an Intel Atom processor running both Windows 7 Home Premium and Android.

One observation here is that while Android per se will emerge as Apple’s biggest OS competitor, the market for Android partners will be highly fragmented, potentially making it somewhat unprofitable. We shall see.